The image formed by a convex mirror of focal length $30 \,cm$ is a quarter of the size of the object. The distance of the object from the mirror is (in $\,cm$)

$A$ point object is placed at a distance of $30 \, cm$ from a convex mirror of focal length $30 \, cm$. Where will the image be formed?

The image formed by a concave mirror is

$A$ student performed the experiment of determination of focal length of a concave mirror by $u-v$ method using an optical bench of length $1.5 \ m$. The focal length of the mirror used is $24 \ cm$. The maximum error in the location of the image can be $0.2 \ cm$. The $5$ sets of $(u, v)$ values recorded by the student (in $cm$) are: $(42, 56), (48, 48), (60, 40), (66, 33), (78, 39)$. The data set$(s)$ that cannot come from the experiment and is (are) incorrectly recorded,is (are):
$(A) (42, 56)$
$(B) (48, 48)$
$(C) (66, 33)$
$(D) (78, 39)$

If the lateral magnification is $-2$ for a virtual object in a spherical mirror,then:

While capturing solar energy for commercial purposes,we use: